Dryer control

ABSTRACT

This control system for a clothes dryer includes a fabric dryness sensing circuit comprising a resistance-capacitance circuit portion, a neon tube, and a thyristor in the form of an SCR operable for initiating termination of the dryness sensing operation. A chime indicating the end of the drying or sensing operation is operable during the cool-down operation in a repeating manner under control of the resistance-capacitance timing circuit.

United States Patent 91 Cotton [451 Jan. 9, 1973 541 DRYER CONTROL3,180,038 4/1965 Chafee ..317/DIG.3

3,271,878 9/1966 Martin ..307/1l8 X [75] Inventor. Curran D. Cotton,Newton, Iowa 3,273,018 9/1966 Goldberg man/45 DT {73] Assignee: TheMaytag Company, Newton, 3,404,466 10/1968 Reid ..34/45 Iowa Filed: March1971 Primary Examiner-Robert K. Schaefer Appl. No.: 124,042

Related US. Application Data Division of Ser. No. 803,687, March 3,1969.

References Cited UNITED STATES PATENTS 7/1970 Beller ..34/45 AssistantExaminer-William J. Smith Attorney-William G. Landwier and Richard L.Ward [57] ABSTRACT This control system for a clothes dryer includes afabric dryness sensing circuit comprising a resistancecapacitancecircuit portion, a neon tube, and a thyristor in the form of an SCRoperable for initiating termination of the dryness sensing operation. Achime indicating the end of the drying or sensing operation is operableduring the cool-down operation in a repeating manner under control ofthe resistancecapacitance timing circuit.

11 Claims, 4 Drawing Figures "z //3 /00 ll/ PATENTED JAN 9 I975 SHEET 3BF 3 M w m I J M 5 ll/ 0 O O 3 5 H 4 O O F't'gr3 X CONTACT CLOSED DmMENTARY- CLOSED WHEN PUSH ROD FULLY DEPRESSED VCONTACT cLos'Eo ONLYOCONTACT OPEN FOLLOWING PERM. PRESS DRYER CONTROL CROSS REFERENCE TORELATED APPLICATION BACKGROUND OF THE INVENTION 1. Field of theInvention This invention relates to a dryer control system and moreparticularly to a circuit for terminating the drying operation.

2. Description of the Prior Art One type of dryer control becoming morefrequently used for effecting automatic termination of the dryingoperation ofa fabric drying apparatus includes a pair of electrodes forsensing the electrical conductivity of the fabrics in the fabrictumbling container. The prior art patents show a number of specificcontrol circuits for determining fabric dryness by means of a sensingcircuit including a resistance-capacitance circuit portion responsive tothe resistance of the fabrics across the electrodes and operable forterminating the drying operation at a preselected dryness conditionThese moisture sensing systems must be operable with a wide variety offabric types including the synthetic fabrics, or treated fabrics,sometimes referred to as having permanent press characteristics.Furthermore, it is necessary-to remove the permanent press fabrics fromthe drying apparatus immediately upon completion of the tumbling toprevent the setting of new wrinkles in the fabrics. It is thereforedesirable and advantageous to provide an audible or visual indicatormeans observable by the operator upon completion of the cycle so thatthe fabrics may be immediately removed from the dryer.

SUMMARY OF THE INVENTION It is an object of the instant invention toprovide an improved fabric dryness sensing circuit operable forterminating the dryness sensing operation at a desired fabric drynesscondition.

It is a further object of the instant invention to provide an improvedfabric dryness sensing circuit comprising a thyristor uniquely adaptablefor energizing actuation means to terminate the dryness operation.

It is a further object of the instant invention to provide an improvedfabric dryness sensing circuit and to provide indicator means associatedwith the dryness sensing circuit operable on completion of the sensingoperation for signalling the termination thereof.

It is a still further object of the instant invention to provide acombined dryness sensing circuit and repeating end-of-cycle indicatormeans utilizing common components to achieve the sensing of dryness andthe timing of the repeating indicator means.

It is yet a further object of the instant invention to provide animproved dryer control including a solenoid responsive to operation of adryness sensing circuit at a selected fabric dryness condition forterminating the dryness sensing operation ad also operable responsive toa timing circuit for actuating an indicator means signal completion ofthe drying operation.

These objects are achieved in a fabric drying apparatus having a drynesssensing circuit comprising a resistance-capacitance circuit portionoperable for sensing the moisture of the fabrics and initiatingtermination of the drying operation. The resistance capacitance circuitportion is also operable for timing a repeating indicator operator uponcompletion of the dryness operation. The dryness sensing circuit and theindicator timing circuit are each operable for energizing an actuationmeans for terminating the dryness operation and energizing the indicatormeans.

Operation of the device and further objects and advantages thereof willbecome evident as the description proceeds and from an examination ofthe accompanying three pages of drawings.

DESCRIPTION OF THE DRAWINGS The drawings illustrate a preferredembodiment of the invention with similar numerals referring to similarparts throughout the several views, wherein:

FIG. 1 is a view of a dryer partially broken away and sectioned andincorporating the control system of the instant invention;

FIG. 2 is an electrical schematic diagram of a preferred circuitembodying the dryness sensing circuit portion and the indicator circuitportion of the instant invention;

FIG. 3 is a chart indicating the operation of various switches of thecircuit of FIG. 2; and

FIG. 4 is a view of a portion of the control components of the circuitof FIG. 2 including the preselection switch, the solenoid, and theindicator chime.

In FIG. 1 of the accompanying drawings is shown a clothes dryerapparatus having a base 10 that serves as a support for upstandingchannel members 11 and 12 which together with cross-piece 14 support thehollow blower housing casting 17. The housing 17 includes a tubularportion 21, a divider wall 20 having a rearwardly flared inner portiondefining an intake into an impeller chamber, and radially directedlongitudinal webs 22 that converge toward a central axis and join with acylindrical bearing retainer member 23. A plurality of segmentalpassageways are therefore defined by the tubular member 21, the bearingretainer member 23, and the supporting webs 22.

Journalled within member 23 is a revoluble drum drive shaft 31 whichprojects from both ends of the housing 17. Fixed to the drum drive shaft31 adjacent the rear of the dryer is a large pulley 33 which is drivenby motor 34 through a motor pulley 36, main drive belt 37, a speedreduction system (not shown) driven by the main drive belt 37, and belt40 driven in turn by the speed reduction system.

The forward end of the drum drive shaft 31 is rigidly connected to thedrum spider member 46 which has radiating spokes 51 that support a rim52.

A horizontally mounted fabric tumbling drum has a rear wall 61 which issecured to rim 52 for support and rotation by shaft 31. Rear drum wall6] is imperforate except for a central exhaust opening defined by thecircular shoulder 55 that is aligned with the blower tubular member 21.The outer periphery of the rear wall 61 is flanged to form a supportingshoulder for the imperforate cylindrical sidewall 65 .which carries theclothes elevating vanes or baffles 66 for tumbling clothing within thedrum 60 during rotation thereof. Cylindrical sidewall 65 is alsoconnected to the front drum wall 67.

The front wall 67 has a centrally located access opening defined byflange 68 and an annular perforate portion 69 located concentricallyaround the annular flange 68. This perforate portion 69 formed byseveral concentric rows of holes serves as the air intake to drum 60.

Cabinet 70 is fastened to the base and encloses the entire dryingmachine. The cabinet has an access opening defined by flange 71 andaligned with the drum access opening thereby allowing both of theflanges 68 and 71 to receive a rearwardly extending portion of the doorgasket 72. The door 73 is hinged and forms a substantially airtight sealwith the gasket 72.

Fastened to the cabinet 70 is a shroud or cowling member 74. Locatedbetween the shroud 74 and the front drum wall 67 is an open coilelectric heating element 75 which extends around the inside of thecowling member 74 to raise the temperature of the air passing throughthe perforate portion 69 into the drum 60. A gas heater may be used inplace of the electrical heating element 75.

Airflow into drum 60 through the perforate area 69 and into the blowerhousing 17 is produced by rotation of the revoluble impeller member 76located in the blower housing 17. The fan pulley 77 formed integrallywith the impeller 76 is driven directly by the driving motor 34 throughthe main drive belt 37. A felt air sealing member 78 encircles the frontperiphery of blower housing 17 and the circular shoulder 55 to preventair from being drawn in at the junction and thus bypassing the heater 75and drum 60.

The blower housing casting 17 supports at least one thermostat 82 whichis connected in series with the heating element 75 to maintain theinterior drum 60 at the proper selected drying temperature. Alsoconnected in series with the heating element 75 is the high limitthermostat 79 which is mounted on an upper part of the shroud member 74so as to disconnect heating element 75 from its source of power in casethe temperature near the front of the drum should rise above apredetermined selected temperature during the operation of the clothesdryer, for instance, in the event of reduced airflow through the drum60.

' In order to measure the electrical conductivity or resistance of thefabrics within the drum 60, as a measure of the condition of dryness ofthe fabrics, electrodes or probes 80 and 81 are mounted within the drum60. In a preferred embodiment, the electrodes are in the form of a pairof elongated conductor members mounted on the crown of each of thebaffle members 66 to provide a contacting surface engageable by thefabrics tumbling within the drum. It will be realized that differentforms of electrodes, or probes, may be used, although the type disclosedherein is a preferred construction.

Electrical energy is supplied to electrode 80, for example, by lead 84that is connected to a brush 85 that engages the stationary slip ring 86while the drum 60 is rotating. The slip ring 86 is mounted on theelectrically insulative air sealing member 78. The slip ring 86 is inturn connected to a lead 90 which runs to the control unit 92. Theelectrode 81 is connected by lead 83 to the rotatable drum 60 andthrough the drum 60, the drive shaft 31, and blower housing 17 to thechassis including the base 10. The chassis is then connected to earthground through a conductor 87 electrically connected with the base 10,for example. Electrode 81 is thus connected to earth ground.

The automatic control unit 92 may be secured to an upper portion of thecabinet. The lead enters the control unit and is connected to thecontrol unit to be described hereinafter.

The baffles 66 are formed of an electrically non-conductive material inorder to insulate the electrodes. The electrodes, however, areelectrically shorted by the contact of wet fabrics during tumbling. Aplurality of baffles may be mounted within the drum and each may beprovided with electrodes 80 and 81 with the electrode pairs beingconnected in parallel for achieving a greater sensitivity of control.

Referring now to FIG. 2 which illustrates the control circuitry for thefabric drying apparatus, there is shown diagrammatically a manuallyoperable preselection means 100, which is also shown in outline form inFIG. 4. The preselection means includes a plurality of switches 101through 108 actuable between open and closed positions, according to thechart of FIG. 3, under control of a plurality of manually actuatablepush buttons 110 through 113 indicated as Regular, Permanent Press,"Damp Dry," and Air Fluff," respectively. The switches 101 through 108are shown collectively at the right side of the diagram of FIG. 2 undercontrol of the push buttons 110 through 113 and are shown schematicallyin the circuit for controlling initiation and termination of the fabricdrying apparatus as will be more fully shown hereinafter. Operation ofthe group of switch members 101-108 between open and closed positions isalso under the control of a selectively energizable solenoid 116, shownin FIG. 4 and indicated schematically in FIG. 2, to terminate the dryingcycle.

The control circuitry of FIG. 2 includes three conductors 118, 119, andthat are selectively connectable with a conventional three-wire 220volt, alternating current supply. For the explanation of the circuitryofFIG. 2, it will be assumed that the conductors 118 andr119 areconnected with the power lines and that the other conductor 120 isconnected to the neutral line.

The chart of FIG. 3 indicates the electrical posture of the preselectionswitches 101-108 upon selection of each of the selectable cyclescorresponding to the push buttons 110-113 and upon operation of theresetting solenoid 116. It is noted, for example, that the preselectionswitch 101 in the heater circuit is closed for each of the Regular,Permanent Press, and Damp Dry cycles. In the explanation of the circuitof FIG. 2, it will be assumed that a Permanent Press cycle has beenselected by the operator and thus selection switches 101, 102, and 108are closed and preselection switches 104, 105

and 106 are open while preselection switches 103 and 107 are momentarilyclosed during the preselection and machine energization process.

The heater 75 is connected between the first and second conductors 118and 119 by a circuit portion including the preselection switch 101, acycling thermostat 82, a high limit thermostat 79, and a centrifugalswitch 123 in the motor 34. The centrifugal switch 123 is normally openbut is operable to a closed position upon energization of the motor 34.

The drive motor 34 is energized by a circuit extending from theconductor 118 through a door switch 124, closed preselection switch 102,a conductor 125, and momentarily closed preselection switch 103 tojunction 127 at one side of the motor 34. The other side of the motor 34is connected to neutral conductor 120. Subsequent to initialenergization of the motor 34, centrifugal switch 126 within the motor 34will operate and 1 a circuit for maintaining operation of the motor willbe completed from the conductor 118 through the door switch 124,preselection switch 102,. and conductors 125, 130, and 131 to the motor34.

A cool-down thermostat 133 is also provided in the circuit to the motor34 and is operable to a closed position at a predetermined temperaturewithin the drum 60 of, for example, 135 F. After the dryer apparatus hasoperated for a period of time with the heat on, the cool-down thermostat133 will close and maintain the motor 34 energized until the temperaturewithin the drum 60 is reduced to 135 F. This cool-down thermostat 133,therefore, provides a fabric cool-down operation following a heat-ondrying operation.

The fabric dryness sensing circuit is energized from the conductor 118,through the door switch 124, selector switch 102, conductor 125, andmomentary switch 103 to junction 127 and then through conductor 134 tothe junction point 132. After the momentary switch 103 opens, a bypasscircuit around switch 103 includes conductors 130 and 131, a motorswitch 126. Thejunction point 132 connects with a resistance networkincluding resistors 136 and 137 and selection switches 104, 105, and106. The circuit continues through the junction 138 to one side of arectifier 135. The other side of the rectifier 135 is connected to aresistor 139 which is in turn connected to ajunction point 141.Extending from the junction point 141 is one circuit portion including aresistor 143 in series with the electrode 80. The other electrode 81 isconnected to the drum 60 and through various electrically conductiveportions of the apparatus, indicated as 144 in FIG. 2, and to an earthground through the earth ground conductor 87. Also connected to thejunction point 141 is a resistor 140 that is in turn connected toajunction 142.

Connected to the junction point 142 is a resistor 146 and a selectorswitch 107 that is connected at its other side to the neutral conductor120 to provide a shunt circuit across the capacitor 145. The capacitor145 is connected to junction 142 on one side and to the neutralconductor 120 on the other side. It will be noted that during thePermanent Press cycle the capacitor 145 may be charged, as the fabricsacross the electrodes 80, 81 become dry, by the d.c. circuit extendingthrough resistors 136 and 137, and through the rectifier 135 andresistors 139 and 140. The rate of charging of the capacitor is selectedto give the desired dryness condition of the fabrics and is determined,in this embodiment, by the amount of resistance in series with thecapacitor 145. The circuit portion including selector switch 107provides a closed loop path for selectively discharging the capacitor145 at the beginning of a cycle through the momentarily closed switch107 to insure a consistent relationship of the charge on capacitor 145to the dryness of the fabrics across the electrodes 80, 81.

A gaseous discharge tube, such as a neon lamp 149, is connected inseries with resistors 155 and 157 and in turn across the capacitor 145.The neon tube 149 normally has an effectively infinite resistance;however, when the charge on the capacitor 145 reaches a predeterminedvalue, the gas is ionized and a circuit is conducted therethrough. Athyristor, in the form of silicon controlled rectifier, or SCR 159,includes a gate portion electrically connected to one side of the neonlamp 149. The gate may be directly connected as in FIG. 2 or alternatelythrough a resistor. Upon the firing of the neon lamp, a circuit iscompleted to the gate of SCR 159, which in turn becomes conductive andcompletes a circuit between the anode 160 and cathode 161 to effectenergization of the solenoid 116 for resetting the selector switchesl0l108 and thereby initiating termination of the drying operation. Thesolenoid energizing circuit is completed from the conductor 118 throughthe door switch 124, selection switch 102, a conductor 163, and selectorswitch 108 to one side of the solenoid 116. The other side of thesolenoid 116 is connected by conductors 164 and 165 to the anode 160 ofthe SCR 159. The cathode 161 of the SCR 159 is connected to the neutralconductor 120. A filter capacitor 169 ad resistor 170 is connected inparallel to the SCR 159.

Energization of the solenoid 116 resets the preselection means 100. Theresetting effects opening of the selection switches 101, 102, and 108,to terminate the sensing operation for the Permanent Press cycle and tode-energize the heater 75. It will be seen from a further analysis ofFIGS. 2 and 3 that even after actuation of the solenoid 116 the motor 34will'remain energized through an auxiliary circuit to effect continuedtumbling of the fabrics within the drum 60'for a cool-down operationunder control of the cool-down thermostat 133. Upon the temperatureofthe air within the drum reaching a predetermined lower temperature,the thermostat 133 will open for de-energizing the motor 34 to terminatethe cycle of operation.

It will also be seen that upon the firing of the neon tube 149responsive to a predetermined dry condition, actuation of the solenoid116 will effect operation of the chime 174 which is shown schematicallyin FIG. 2 and in outline form in FIG. 4. This one-time operation of thechime will occur at the end of each cycle of operation. Subsequent tothe-completion of the sensing. operation and during the cool-downoperation for a Permanent Press cycle of operations, however, thesolenoid 1l6will be periodically re-energized for effecting a repeatingchime under control of a timing circuit operable during the cool-downoperation as will be more fully explained hereinafter. This repeatingchime during the cool-down portion of the Permanent Press cycle ofoperations in this embodiment signals the operator so that the fabricsmay be immediately removed following the end of the tumbling to preventthe forming of wrinkles in the fabrics.

Referring to FIG. 4, the structure and interrelationship of the solenoid116, preselection means 100, and chime 174 will now be more fullydescribed. The preselection means 100, the solenoid 116; and the chime174 are mounted to a panel 175 of the dryer'apparatus through a bracket176 attached to thepanel 175 with a plurality of screws 179. Thepreselection means 100 is mounted to the bracket 176-so that the pushbuttons 110-113 are accessible to theoperator and selectively operablefor initiatinga desired cycle of operations. The solenoid 116' ismounted to the bracket 176 and is linked to a switch actuating member180 through the linkage 181. The chime 174 includes a bell member 183engageable by a hammer 184 that is attached through a spring member 185to the mounting bracket 176. Actuation of the solenoid 116 will move theswitch actuating member 180 toward the solenoid for resetting theswitches within the preselection means 110. The actuation of thesolenoid 116 will also move the chime hammer 184 for effectingengagement thereof with the chime bell 183.

During the cool-down operation a timing circuit is completed to theresistance-capacitance portion of the circuit of FIG. 2 and an actuationcircuit is periodically completed to the solenoid 116 through thecurrentlimiting resistor 189 connected in parallel with the selectorswitch 108. More specifically, a timing circuit is completed to thejunction 127 through the door switch 124, cool-down thermostat 133,conductor 131, and switch 126. From junction 127, the circuit iscompleted to junction 132 through conductor 134. It will be seen fromFIG. 3 that selection switch 106 is closed during the cool-downoperation of a Permanent Press cycle only, so that a circuit iscompleted from the junction 132 to the resistance-capacitance portion ofthe circuit including rectifier 135.

Thus during the cool-down operation ofa Permanent Press cycle, and withthe fabrics substantially dry as sensed by the dryness sensing control,there will be a charging of the capacitor 145 in a manner as previouslydescribed except that less resistance is in series with the capacitor145, since resistors 136 and 137 are bypassed. The capacitor 145 willtherefore charge over a relatively short predetermined time period foractuating the neon tube 149 and gating the SCR 159. The gating of theSCR 159 will complete a circuit to the solenoid 116 for energizing thesolenoid at a reduced power level, however, because of the open switch108 resulting in the completion of the circuit through the currentlimiting resistor 189. The circuit extends from the conductor 118through the door switch 124, the cool-down thermostat 133, theconductors 130, 125, and 163 and the resistor 189 to one side of thesolenoid 116. The other side of the solenoid is connected to the neutralconductor 120 through the anode-cathode path of the SCR 159. Thecharging of the capacitor 145 and the firing of the SCR 159 forenergizing the solenoid 116 will continue during the cool-down operationin the Permanent Press cycle for repeatedly energizing the solenoid witha frequency of energization determined by the R-C constant of theresistance- .capacitance circuit portion.

As previously indicated, the solenoid 116 is periodically actuated at alower power level during the cooldown operation under timing control ofthe resistancecapacitance circuit portion. Since the switches l01-108are already in the reset position, the lower 1 power output of thesolenoid 116 is sufficient for overcoming the spring pressure on thechime hammer 184 and effecting actuation of the chime 174 for issuing anaudible signal.

Thus it is seen that a repeating chime indicating the end of a PermanentPress cycle of operations, for example, is achieved with substantiallyno addition of components. Solenoid 116 is operable for achieving thedual operation of terminating the operation by resetting thepreselection means 100 while also being operable at a reduced powerlevel for actuating the repeating chime 174 during the cool-downoperation. Furthermore, the use of the resistance-capacitance portion ofthe sensing circuit provides timing of the chime and thus eliminates theneed for an auxiliary timer. Still further, the use of the SCR permitsan energization of the solenoid at the completion of the sensingoperation and also a cyclic energization for operating the repeatingchime, and thus the need for an auxiliary circuit for cyclicallyenergization the solenoid is eliminated.

in the drawings and specification, there has been set forth a preferredembodiment of the invention and although specific terms are employedthese are used in a generic and descriptive sense only and not forpurposes of limitation. Changes in form and the proportion of parts aswell as the substitution of equivalents are contemplated ascircumstances may suggest or render expedient without departing from thespirit or scope of this invention as further defined in the followingclaims.

1 claim:

1. In a fabric dryness sensing circuit, the combination comprising:manually actuatable means for initiating a dryness sensing operation;electrode means engageable with fabrics for completing an electricalcurrent path to said fabrics during said dryness sensing operation;resistance means and capacitance means in circuit with said electrodemeans; electrical supply means connected in circuit with said electrodemeans, said resistance means, and said capacitance means; a normallynon-conductive electronic discharge device in parallel connection tosaid capacitance means and operable to a conductive condition at apredetermined voltage, said capacitance means being chargeable to saidpredetermined voltage at a preselected dryness condition of the fabricsengageable with said electrode means and operable at said predeterminedvoltage for energizing said discharge device; and control meansincluding a control member for operating said manually actuatable meansand a thyristor having a gate portion in circuit with said dischargedevice and an anodecathode portion in circuit with said control member,said thyristor being operable at said predetermined voltage from anormally non-conductive posture across said anode-cathode portion to aconductive posture for in turn energizing said control member to operatesaid manually actuatable means for terminating said dryness sensingoperation.

2. In a fabric dryness sensing circuit, the combination comprising:manually actuatable means for initiating a fabric dryness sensingoperation; electrode means engageable with fabrics for completing anelectrical current path to said fabrics during said fabric drynesssensing operation; resistance means and capacitance means in circuitwith said electrode means; electrical supply means connected in circuitwith said electrode means, said resistance means, and said capacitancemeans; a normally non-conductive electronic discharge device in parallelconnection to said capacitance means and operable to a conductivecondition at a predetermined voltage, said capacitance means beingchargea' ble to said predetermined voltage at a preselected drynesscondition of the fabrics engageable with said electrode means andoperable at said predetermined voltage for energizing said dischargedevice; and control means for terminating said dryness sensing operationat said preselected fabric dryness condition and includingelectromechanical actuation means for operating said manually actuatablemeans and a thyristor for energizing said actuation means, saidthyristor having an anode-cathode portion in series with said actuationmeans and a gate portion electrically connected to said discharge deviceand responsive to said predetermined voltage for triggering saidthyristor to terminate said dryness sensing operation throughenergization of said actuation means for operating said manuallyactuatable means.

3. In a fabric dryness sensing circuit as defined in claim 2 whereinsaid actuation means includes a solenoid controlled by said thyristorand operable for effecting termination of said dryness sensingoperation.

4. In a fabric dryness sensing circuit as defined in claim 2 whereinsaid thyristor is in the form of a normally non-conductive SCR operableto a conductive condition responsive to energization of said dischargedevice. 5

5. In a fabric dryness sensing circuit as defined in claim 2 whereinsaid actuation means includes a solenoid having a coil and wherein saidthyristor is in the form of a normally non-conductive SCR in series withsaid solenoid coil and responsive to energization of said dischargedevice for energizing said solenoid coil.

6. In a fabric dryness sensing circuit as defined in claim 4 whereinsaid discharge device is in the form ofa neon tube.

7. In a fabric dryness sensing circuit, the combination comprising:manually actuatable means for initiating a fabric dryness sensingoperation; electrode means engageable with fabrics for completing anelectrical current path to said fabrics during said fabric drynesssensing operation; resistance means and capacitance means in circuitwith said electrode means; electrical supply means connected in circuitwith said electrode means, said resistance means, and said capacitancemeans; a normally non-conductive electronic discharge device in parallelconnection to said capacitance means and operable to a conductivecondition at a predetermined voltage said capacitance means beingchargeable to said predetermined voltage at a preselected drynesscondition of the fabrics engageable with said electrode means andoperable at said predetermined voltage for energizing said dischargedevice; solenoid means energizable for operating said manuallyactuatable means to terminate said dryness sensing operation; andcircuit means including a thyristor operable for effecting energizationof said solenoid means at said preselected fabric dryness condition,said thyristor having a gate portion electrically connected to saiddischarge device and operable at said predetermined voltage fortriggering said thyristor to energize said solenoid means for operatingsaid manually actuatable means and terminating said dryness sensingoperation.

8. In a fabric dryness sensing circuit, as defined in claim 7 whereinsaid thyristor is in the form of an SCR in series with said solenoidmeans and responsive to said discharge device for energizing saidsolenoid means.

9. In a fabric dryness sensing circuit as defined in claim 8 whereinsaid discharge device is in the form of a neon TG. in a drying apparatuscontrol circuit, the

combination electrode means engageable with fabrics for completing anelectrical current path to said fabrics during a fabric dryness sensingoperation; resistance means and capacitance means in circuit with saidelectrode means; electrical supply means connected in circuit with saidelectrode means, said resistance means, and said capacitance means; anormally non-conductive electronic discharge device in parallelconnection to said capacitance means and operable to a conductivecondition at a predetermined voltage, said capacitance means beingchargeable to said predetermined voltage at a preselected drynesscondition of the fabrics engageable with said electrode means andoperable at said predetermined voltage for energizing said dischargedevice; SCR means including a gate portion electrically connected tosaid discharge device and responsive to energization of said dischargedevice for actuating said SCR means to a conductive condition; solenoidmeans connected in series with said SCR means and operable to anenergized condition upon actuation of said SCR means; and preselectionmeans manually actuatable for initiating a drying operation of saiddrying apparatus and for initiating said dryness sensing operation andfurther operable to a reset condition responsive to energization of saidsolenoid means for initiating termination of said drying and saiddryness sensing operations.

said manual actuation for initiating a selected one of said dryingoperations and responsive to energizaton of said solenoid means foraction to said reset condition for terminating the selected dryingoperation.

mums STATES PATENE OFFECE @F CORRECTICN Patent No. ,71 ,138 DatedJanuary 9, 19-73.

In Curran D. Cotton I It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Col. 1, line 64 "ad" should be and Col. 1, line 65 after "means" add toCol.- 2, line 5 "operator" should be operable Col. 4, line 18 "actuable"should be actuatable Col. 5, line 26 "a" should be and Col. 6, line 21"ad" should be and Col 8 line 10 "energization" should be energizingClaim 7, line 43 afterr'z"voltage" insert Claim 9, line 13 after "neon"add tube Claim 10, linelS after "combination" add eoinprisingr -r.

Claim 11, line 50 "action" should be actuation Signed and sealed this29th day of May 1973.

LSEAL) Attest! EDWARD M.FLET( IHER,JR. ROBERT GOTTSC HALK A AttestlngOfficer Commissioner of Patents FORM PO-lOSO (10-69) USCOMM'DC @037",

* ".8. GOVERNMENT HUNTING OI'ICI I"; 0-!

UNETED STATES PATENE OFFKCE CEE'IWECATE CF CCEECTICN Patent No'.3,710,138 Dated January 9, 19 73.

Inventor) Curran D. Cotton It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Col. 1, line 64 "ad" should be and Col. 1, line 65 after "means" add toCol. 2, line 5 "operator" should be operable.

Col. 4, line 18 "actuable" should be actuatable Col. 5, line 26 "a"should be and Col. 6, line 21 'ad should be and Col.- 8 line 10"energization" should be energizing Claim 7, line 43 afterr': "voltage"insert Claim 9, line 13 after "neon" add tube Claim 10, line 15 after"combination" add qomprising z I Claim ll, line 50 "action" should beactuation Signed and sealed this 29th day of May 1973.

( SEAL) Attestz EDWARD M.FLBT( IHER,JR. ROBERT GOTTSCHALK A AttestingOff cer Commissioner of Patents- FORM PC4050 ($69) uscoMM-Dc 90376 ".5.GOVERNMENT PRINTING OFFICE 1 0-3

1. In a fabric dryness sensing circuit, the combination comprising:manually actuatable means for initiating a dryness sensing operation;electrode means engageable with fabrics for completing an electricalcurrent path to said fabrics during said dryness sensing operation;resistance means and capacitance means in circuit with said electrodemeans; electrical supply means connected in circuit with said electrodemeans, said resistance means, and said capacitance means; a normallynon-conductive electronic discharge device in parallel connection tosaid capacitance means and operable to a conductive condition at apredetermined voltage, said capacitance means being chargeable to saidpredetermined voltage at a preselected dryness condition of the fabricsengageable with said electrode means and operable at said predeterminedvoltage for energizing said discharge device; and control meansincluding a control member for operating said manually actuatable meansand a thyristor having a gate portion in circuit with said dischargedevice and an anode-cathode portion in circuit with said control member,said thyristor being operable at said predetermined voltage from anormally nonconductive posture across said anode-cathode portion to aconductive posture for in turn energizing said control member to operatesaid manually actuatable means for terminating said dryness sensingoperation.
 2. In a fabric dryness sensing circuit, the combinationcomprising: manually actuatable means for initiating a fabric drynesssensing operation; electrode means engageable with fabrics forcompleting an electrical current path to said fabrics during said fabricdryness sensing operation; resistance means and capacitance means incircuit with said electrode means; electrical supply means connected incircuit with said electrode means, said resistance means, and saidcapacitance means; a normally non-conductive electronic discharge devicein parallel connection to said capacitance means and operable to aconductive condition at a predetermined voltage, said capacitance meansbeing chargeable to said predetermined voltage at a preselected drynesscondition of the fabrics engageable with said electrode means andoperable at said predetermined voltage for energizing said dischargedevice; and control means for terminating said dryness sensing operationat said prEselected fabric dryness condition and includingelectromechanical actuation means for operating said manually actuatablemeans and a thyristor for energizing said actuation means, saidthyristor having an anode-cathode portion in series with said actuationmeans and a gate portion electrically connected to said discharge deviceand responsive to said predetermined voltage for triggering saidthyristor to terminate said dryness sensing operation throughenergization of said actuation means for operating said manuallyactuatable means.
 3. In a fabric dryness sensing circuit as defined inclaim 2 wherein said actuation means includes a solenoid controlled bysaid thyristor and operable for effecting termination of said drynesssensing operation.
 4. In a fabric dryness sensing circuit as defined inclaim 2 wherein said thyristor is in the form of a normallynon-conductive SCR operable to a conductive condition responsive toenergization of said discharge device.
 5. In a fabric dryness sensingcircuit as defined in claim 2 wherein said actuation means includes asolenoid having a coil and wherein said thyristor is in the form of anormally non-conductive SCR in series with said solenoid coil andresponsive to energization of said discharge device for energizing saidsolenoid coil.
 6. In a fabric dryness sensing circuit as defined inclaim 4 wherein said discharge device is in the form of a neon tube. 7.In a fabric dryness sensing circuit, the combination comprising:manually actuatable means for initiating a fabric dryness sensingoperation; electrode means engageable with fabrics for completing anelectrical current path to said fabrics during said fabric drynesssensing operation; resistance means and capacitance means in circuitwith said electrode means; electrical supply means connected in circuitwith said electrode means, said resistance means, and said capacitancemeans; a normally non-conductive electronic discharge device in parallelconnection to said capacitance means and operable to a conductivecondition at a predetermined voltage said capacitance means beingchargeable to said predetermined voltage at a preselected drynesscondition of the fabrics engageable with said electrode means andoperable at said predetermined voltage for energizing said dischargedevice; solenoid means energizable for operating said manuallyactuatable means to terminate said dryness sensing operation; andcircuit means including a thyristor operable for effecting energizationof said solenoid means at said preselected fabric dryness condition,said thyristor having a gate portion electrically connected to saiddischarge device and operable at said predetermined voltage fortriggering said thyristor to energize said solenoid means for operatingsaid manually actuatable means and terminating said dryness sensingoperation.
 8. In a fabric dryness sensing circuit, as defined in claim 7wherein said thyristor is in the form of an SCR in series with saidsolenoid means and responsive to said discharge device for energizingsaid solenoid means.
 9. In a fabric dryness sensing circuit as definedin claim 8 wherein said discharge device is in the form of a neon cm 10.In a drying apparatus control circuit, the combination electrode meansengageable with fabrics for completing an electrical current path tosaid fabrics during a fabric dryness sensing operation; resistance meansand capacitance means in circuit with said electrode means; electricalsupply means connected in circuit with said electrode means, saidresistance means, and said capacitance means; a normally non-conductiveelectronic discharge device in parallel connection to said capacitancemeans and operable to a conductive condition at a predetermined voltage,said capacitance means being chargeable to said predetermined voltage ata preselected dryness condition of the fabrics engageable with saidelectrode means and operable at said predetermined voltage forenergizing said discharge device; SCR means inclUding a gate portionelectrically connected to said discharge device and responsive toenergization of said discharge device for actuating said SCR means to aconductive condition; solenoid means connected in series with said SCRmeans and operable to an energized condition upon actuation of said SCRmeans; and preselection means manually actuatable for initiating adrying operation of said drying apparatus and for initiating saiddryness sensing operation and further operable to a reset conditionresponsive to energization of said solenoid means for initiatingtermination of said drying and said dryness sensing operations.
 11. In adrying apparatus control circuit as defined in claim 10 wherein saidpreselection means includes a plurality of switches operable betweenopen and closed positions for providing a plurality of selectable dryingoperations and wherein said switches are responsive to said manualactuation for initiating a selected one of said drying operations andresponsive to energizaton of said solenoid means for action to saidreset condition for terminating the selected drying operation.